The use of randomized clinical trials to evaluate drugs and medical devices is a complex and increasingly expensive process, which is plagued by disappointingly low rates of success. Innovations in clinical trial methodology, and specifically adaptive clinical trials, can address many ofthe limitations of conventional trial designs and have the potential to improve the efficiency and success rates of clinical research, the quality of resulting scientific data, and the protection of human subjects. Optimal approaches-including both statistical methods and organizational processes-iforthe collaborative development and implementation of confirmatory, adaptive clinical trials remain unclear. This project will address that gap. The process of clinical trial development within the NINDS-supported Neurological Emergencies Treatment Trials (NETT) networl< will be used as the laboratory in which to study the development of these trials. The overall objective ofthe proposed worl< is to illustrate and explore how best to use adaptive clinical trial designs to improve the evaluation of drugs and medical devices and to use mixed methods to characterize and understand the beliefs, opinions, and concerns of key stal<eholders during and after the development process. The first specific aim is to design four innovative, adaptive clinical trials for the evaluation of drugs and devices used in the care of patients with acute neurological illness or injury. The adaptive methods will include frequent interim analyses, probability-based decision rules, longitudinal modeling of unl<nown outcomes, and response-adaptive randomization. The second specific aim is to identify and qualitatively characterize l<ey steps and barriers related to the acceptance and implementation of adaptive clinical trials. After acceptance of one or more adaptive clinical trial designs by key stakeholders, the designs will be incorporated into grant applications submitted for funding and peer review. RELEVANCE (See Instructions): Randomized clinical trials are the cornerstone for acceptance of new therapies by regulatory agencies and clinicians. Currently, this process is slow and cumbersome and may lead to false conclusions about the utility of new treatments. This project will identify effective processes for the design and initiation of high-quality, confirmatory, adaptive clinical trials. These methods can be used to accelerate the evaluation of promising new therapies, conserve resources and support public health by improving the rate and quality of drug and device development.